In recent years, compactness and high output have been required in rotary electric machines such as electric motors or generators. With regard to downsizing rotary electric machines of this kind, stator windings that have concentrated windings in which conductor wires are wound onto individual stator core teeth have been used with a view to downsizing coil ends that do not generate effective magnetic flux. However, stators that use stator windings of distributed winding construction that can suppress torque pulsation and increase output are also in demand.
Now, in contrast to concentrated windings, which are configured by winding conductor wires onto individual teeth, windings that are configured by winding conductor wires into slots that are separated by greater than or equal to two slots are called “distributed windings”. In other words, distributed windings are wound such that a conductor wire that extends outward from one slot spans two or more consecutive teeth and enters another slot.
In conventional rotary electric machines such as that described in Patent Literature 1, winding coils that are molded into a coil shape by winding for a plurality of times a conductor wire that is coated with insulation, also known as “hexagonal coils”, are housed in respective pairs of slots that are separated by a plurality of slots to constitute a distributed winding stator winding. Vertex portions of coil end portions are formed into crank shapes so as to be offset by an entire width of the conductor wire that is wound for a plurality of times such that the hexagonal coils are housed in an inner layer side of a first slot and an outer layer side of a second slot, and an insulating layer is applied to the coil end portions to ensure interphase insulation.
In conventional rotary electric machines such as that described in Patent Literature 2, winding groups that are formed by arranging at a pitch of one slot windings in which conductor wires are inserted into respective slots that are separated by a plurality of slots in a circumferential direction so as to be mounted in a wave shape are disposed in multiple layers radially to form a distributed-winding stator winding. A thick insulating coating is coated onto the conductor wire, or insulating papers are disposed between the conductor wire, to ensure interphase insulation.